A Fusionless Scoliosis Correction Device (J. Talsma)

Designing a Fusionless Scoliosis Correction Device

Introduction

Scoliosis is a term that diagnoses a lateral curvature of the spine. Any spine with a measured lateral Cobb-angle of more than 10° is considered to be scoliotic (see figure). The curve can be either C or S shaped. The C shape is formed during growth when the spine forms one curve, the S shape occurs when two curves are formed. Besides this lateral curvature, a rotational curvature of variable magnitude is nearly always present. If this disease stays untreated, the deformity is very likely to deteriorate with the consequence that the patient will have an adult life of pain, disability, low self-esteem, cardio-respiratory complications and even premature death.

Therefore, it has been tried to treat scoliosis and reduce the curvature for a long time. Commonly used methods are bracing and surgery. When Cobb-angles are between 20 and 40 degrees, no surgery is performed. Instead, scoliosis is treated with an orthosis, such as the Milwaukee brace and the Boston brace (see figure). Braces cannot correct the deformity, but can sometimes stop progression of the curve. Especially for this group of patients, non-fusion surgery is demanded. When Cobb-angles exceed 40 degrees, usually fusion surgery is performed. Typical fusion surgery procedures involve attaching rods to the posterior of the spine like Harrington, Luque and Cotrel and Dubousset rods (see figure). A full correction of the spine can be achieved, but the stiff metal rods cause the vertebrae to fuse together. Result: a straight and stable spine, but a complete loss of flexibility. This surgery cannot be reversed.

Objectives

Main goal of this assignment is to develop a new correction device, which will be attached to the spine and correct the scoliosis. The aim is to obtain a full correction of the lateral curvature. The associated axial rotation in an idiopathic scoliosis should also be corrected. The new correction system has to prevent the vertebrae from fusing to maintain a full range of motion. After correction, it must be possible to remove the device from the body.

Methods

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First of all a literature study is carried out. In the following analysis phase the problem is defined, the requirements of the device are formulated as well as its functions.

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The second phase is the syntheses. Solutions are found for the different functions. Concepts are formed out of these solutions and the best concept will be further developed. After this, a prototype can be produced.